3.6 Operator tripping facilities
It is normal practice to provide some direct mechanical means of tripping the turbine from the front pedestal. Originally, this was an essential safeguard for personnel when carrying out overspeed tests — either on-load oil-injection tests or off-load tests actually overspeed-ing the machine.
This form of trip is still retained, even where complete remote testing can be carried out, as it provides an independent and very direct means of shutting down the turbine-generator, should a plant attendant observe local conditions which are hazardous to men or the machine. For the same reason an electrically-signalled pushbutton trip is provided near the generator-end of the machine.
A remote emergency stop pushbutton is also provided in the control room, where the operator has various instruments to guide him. Typically, the operator may decide to trip the machine in the event of persistent high vibration. This pushbutton is also the normal means of shutting down a turbine from a low load.